Dual Control Circuit Logic for Vehicle Power Isolation
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Solution Overview
Problem
Existing on-vehicle power source systems face challenges in reliably switching off a switch between power storage devices during a ground fault, particularly when a single ECU fails, leading to potential contamination between power systems.
Innovation Solution
An on-vehicle power source switch apparatus featuring a separation switch controlled by dual control circuits and a logic circuit, which ensures the switch is switched off even if one control circuit malfunctions, and includes additional switches and voltage detection circuits for precise charge rate calculation and independent system operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ECU controls the semiconductor switch, then the control structure is simple, but the reliability of switching off the switch during ground fault decreases
Solution Approach 1:
The control structure is segmented into two independent control circuits (first control circuit and second control circuit) that separately monitor and control the semiconductor switch. This segmentation ensures that if one control circuit fails, the other can still reliably switch off the semiconductor switch during ground faults, thereby improving switching reliability without significantly increasing overall system complexity.
Solution Approach 2:
The system implements beforehand cushioning by providing redundant control circuits that stand ready to take over if the primary control fails. The logic circuit is designed to accept inputs from either control circuit and execute the switching operation, ensuring that reliability is cushioned against control circuit failures before they occur.
2Reliability
If dual control circuits are used to improve reliability, then the switching reliability increases, but the device complexity increases
Solution Approach 1:
The two control circuits are merged through a common logic circuit that processes signals from both circuits. This merging approach allows the system to maintain high reliability through redundant control paths while avoiding the complexity of two completely independent control systems. The logic circuit consolidates the decision-making function, reducing overall structural complexity.
Solution Approach 2:
The logic circuit serves multiple functions: it receives control signals from either the first or second control circuit, determines the appropriate switching state, and controls the semiconductor switch. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby limiting the increase in device complexity while maintaining high reliability.
3Reliability
If the separation switch is controlled to switch off during ground fault, then the isolation of fault is achieved, but the power supply continuity may be affected
Solution Approach 1:
The power supply system is segmented into multiple independent paths including the first power storage device, second power storage device, and their respective control circuits. When a ground fault occurs and the separation switch is turned off, the fault is isolated to one segment while other segments continue to supply power, maintaining power supply continuity without compromising fault isolation.
Solution Approach 2:
The system provides beforehand cushioning by having redundant power supply paths prepared in advance. When the separation switch isolates a fault, the remaining power supply paths are already configured to maintain power delivery, ensuring that power supply continuity is cushioned against the interruption caused by fault isolation.
Data Source
AI summary
An on-vehicle power source switch apparatus configured to switch off a switch when a ground fault occurs is provided. A first system includes a generator, a first power storage that powers a first vehicle load. A second system includes a second power storage device that powers a second vehicle load. A separation switch is connected between the first and the second systems. A first and a second control circuits respectively output a first and a second provisional control signals for controlling the separation switch. A logic circuit switches on the separation switch when both the first and the second provisional controls signal indicate on. When power is generated, the first and the second control circuits output respective first and second provisional control signals indicating on, and when a ground fault has occurred, the first and second control circuits output the first and second provisional control signals indicating off.